Wildcat Lake residents will be detoured up to five miles the next couple months while contractors replace a fish-blocking culvert.

The deteriorating pipe, a short distance down Wildcat Lake Road, carries Wildcat Creek out the east end of the lake. Anybody across the creek will have to drive the long way around the lake, via Holly Road. Temporary roads are sometimes built during culvert projects, but the ravine here is too deep.

"Both permitting and cost-wise, it just didn't pencil out to do a single-lane bypass," said Tim Beachy, project manager for Kitsap County Public Works. "Also in this case there is a definite detour route."

RV Associates will replace the pipe culvert with a 23-foot-wide, 85-foot-long concrete bridge. Work will begin Monday and continue through Oct. 1. The Port Orchard firm was the lowest of six bidders, at $428,000. The county had estimated the job at $532,000.

Though fish aren't totally blocked by the culvert, the county rates it as its fourth-most-significant barrier. Wildcat Creek is a tributary of Chico Creek, Kitsap Peninsula's most productive salmon stream, and a gateway to the enriching lake. The rating applies to fish passage only, not the cost or difficulty of the project, which could juggle the calendar.

Jon Oleyar, a biologist for the Suquamish Tribe, has lobbied for eight years to replace the culvert.

"Coho, chum, steelhead and even cutthroat have the ability to get up into the lake and spawn in a variety of tributaries up there," he said. "That lake is such an important nursery for juvenile salmon. Conditions there are so incredibly more productive than if they had to spend their lives in the creek. In the lake, they can grow bigger, faster and head out to saltwater when they're ready and survivability is much more increased by having that lake up there." The culvert can't handle storm flows. It becomes a water cannon, scouring out a pool at the downstream end, Oleyar says. The sharp, jagged pipe winds up a foot or two over the water. The past couple years, the county has placed sandbags to give fish a lift.

Fish can wait days until conditions are right for them to jump into the pipe. All the while, they try, getting bruised, beaten and sometimes eaten.

"Salmon, once they enter fresh water, their clock is ticking," Oleyar said. "They need to get to their spawning grounds as quickly as they can. When you have barriers like this culvert, they get stuck there. They can only last so many weeks in fresh water until they succumb and die."

The goal, Oleyar says, is to make the culvert passable for fish going in or out of the lake any time of year, during low water or high water.

The Suquamish Tribe has the lead on the county's top-rated fish barrier — Chico Creek at Kitty Hawk Drive, said county engineer Jon Brand. The "fairly complex" project is in the design stage. The county has invested $200,000 in it so far. It was close to being built this year, Brand said.

Another Chico Creek project is No. 2 on the list — at Golf Club Hill Road. The 30 percent design is completed and now the county's Department of Community Development, which is heading the project, is searching for funding, said the DCD's Steve Heacock. It's a major undertaking — replacing a triple box culvert with a bridge.

At No. 3 is Burley Creek at Bethel Burley Road near Fenton Road. That was delayed because of workload issues, Brand said. It's scheduled for 2014-15.